1. Technical Field
This invention relates generally to hand tools, and more particularly to an electric drill or other handheld rotary power unit with a quick-release chuck assembly.
2. Description of Related Art
An existing electric drill, screwdriver, or other handheld rotary power unit often has a quick-release chuck assembly. A typical quick-release chuck assembly includes a sleeve that is spring biased in a locked position. The user slides the sleeve axially relative to the rest of the chuck assembly (e.g., forwardly) to an unlocked position, and then inserts or removes a screwdriver bit, drill bit, or other tool. Releasing the sleeve allows it to slide back to the locked position under influence of the spring biasing.
This arrangement is popular. It foregoes the need for a chuck key and the inconvenient and time-consuming task of keeping and using a chuck key. But certain problems remain. To better visualize one problem, consider in further detail the steps involved in removing a drill bit from the quick-release chuck assembly of an electric drill.
First, the user grasps the forward portion of the electric drill with one hand (e.g., his left hand) while placing the rearward or handle portion of the electric drill against his belt or torso. Holding the electric drill that way frees the user's right hand so that he can grasp the drill bit with it. Now, with the electric drill held against the belt or torso with the left hand and the drill bit grasped with the right hand, the user slides his left hand forwardly to grasp the sleeve portion of the chuck assembly. Then, he slides the sleeve forwardly to the unlocked position with his left hand while removing the drill bit with his right hand. After that, he releases the sleeve so that it can return to the rearward locked position. He can then proceed to insert a different drill bit in much the same way.
From the foregoing, one might say that the existing quick-release chuck assembly really requires three hands. The user requires one hand to hold the electric drill, a second hand to hold the drill bit, and a third hand to slide the sleeve. Placing the electric drill against the belt or torso enables the user to use just two hands, but operating the chuck that way is a somewhat cumbersome task. Thus, users need a better quick-release chuck assembly.